The projects in the SCOR will all utilize the Myocardial Cell Biology Core Unit, which is designed to provide purified cultures of neonatal rat myocardial cells for the various projects. In many cases, the cultured cells will be used to identify candidate signaling molecules and pathways that can activated hypertrophy in the in vitro cultured myocardial cell system. The cell system has been extremely well-characterized, and numerous approaches for documenting cause-effect relationships between specific signaling molecules and the activation of a hypertrophic response have been developed. This Core Unit will assist in providing the cultured cells, and any other assistance related to the use of the in vitro assay system. In addition to providing purified cultures of neonatal rat ventricular myocardial cells, this Core Unit will also provide neonatal and adult mouse cardiac myocytes. Our laboratory has extensive experience in the culturing of embryonic, neonatal and adult mouse cardiac myocytes. our laboratory has extensive experience in the culturing of embryonic, neonatal, and adult muscle cells from various cardiac chamber compartments. Another important function of the Core is to generate recombinant adenoviral vectors for gene transfer in neonatal rat myocardial cells and in the in vivo heart context. In certain cases, adenoviral vectors will primarily be utilized in cultured myocardial cells to direct the expression of dominantly active signaling molecules. Our laboratory has extensive experience with adenoviral mediated gene transfer. Accordingly, there are five specific functions for this Core unit: a) To provide purified cultures of neonatal mouse and rat ventricular myocardial cells and related techniques for gen transfer in these cells. b) To provide purified adult ventricular muscle cells from various transgenic and gene-targeted mouse lines for analysis. c) To generate and utilize recombinant adenoviral vectors for gene transfer in neonatal rat myocardial cells for various projects in the Program. d) To utilize new strategies for high efficiency somatic gene transfer in the post-natal mouse heart. e) To provide a mechanical stretch induced hypertrophy assay system for wildtype and mutant neonatal mouse myocardial cells.